Answer:
Mean: 40.17 years.
Standard deviation: 10.97 years.
Step-by-step explanation:
The frequency distribution is in the attached image.
We can calculate the mean adding the multiplication of midpoints of each class and frequency, and dividing by the sample size.
The midpoints of a class is calculated as the average of the bounds of the class.
Then, the mean can be written as:
The standard deviation can be calculated as:
Answer:
Step-by-step explanation:
Hello, please consider the following.
So this is divisible by 3.
Now, to prove that this is divisible by 9 = 3*3 we need to prove that
is divisible by 3. We will prove it by induction.
Step 1 - for n = 1
4+17=21= 3*7 this is true
Step 2 - we assume this is true for k so is divisible by 3
and we check what happens for k+1
is divisible by 3 and
is divisible by 3, by induction hypothesis
So, the sum is divisible by 3.
Step 3 - Conclusion
We just prove that is divisible by 3 for all positive integers n.
Thanks